The present invention relates to refrigeration systems. More particularly, the present invention relates to distributed refrigeration systems for trailers.
Large trucks (e.g., semi-tractor trailers) are commonly used to store and transport cargo, such as food product, within a trailer at a reduced or refrigerated temperature. Typically, the trailer includes a refrigeration system to maintain the cargo at the reduced temperature. One common type of refrigeration system includes a refrigeration unit having a compressor directly driven by a diesel engine and belt-driven condenser and evaporator fans. Another common type of refrigeration system includes a refrigeration unit that is electrically driven by an alternator coupled to the engine.
In either scenario, a single refrigeration unit is generally located on a front wall of a container of the trailer. The refrigeration unit typically must provide cooling to the entire container, even though some containers may be up to fifty-three feet long in trailers and seventy-two feet long in rail cars. As such, a powerful air circulation system is required to maintain a uniform temperature throughout the trailer. However, the energy required to operate the air circulation system and move air from one end of the container to another substantially reduces the overall efficiency of the refrigeration system.
In addition, if the container includes multiple compartments or portions that should be cooled to different temperatures, the complexity of the refrigeration system is greatly increased. For example, lengthy piping and additional flow control valves are commonly required to maintain different portions of the container at different temperatures, increasing the risk of refrigerant leaks and lowering the overall energy efficiency of the refrigeration system.